NIH Study: Most Homes Have High Levels of Allergens

More than 90 percent of homes in the United States have three or more detectable allergens present, with 73 percent having at least one allergen at elevated levels, a scenario that one family physician expert says could spell trouble for sensitized patients.

"Elevated allergen levels can exacerbate symptoms in people who suffer from asthma and allergies, so it is crucial to understand the factors that contribute," said Darryl Zeldin, M.D., senior author and scientific director at the NIEHS, in a related news release.(www.nih.gov)

Family Physician's Perspective

Jennifer Frost, M.D., medical director for the AAFP Health of the Public and Science Division, told AAFP News that although most people are exposed to allergens in their home, they don't all manifest allergy symptoms.

Story Highlights

A National Institute of Environmental Health Sciences study found that more than 90 percent of homes in the United States have three or more detectable allergens present.

Using data from the 2005-06 National Health and Nutrition Examination Survey, researchers studied levels of allergens from eight common sources -- cat, dog, cockroach, mouse, rat, mold and two types of dust mite allergens -- in the bedrooms of nearly 7,000 U.S. homes.

The AAFP previously endorsed the American Academy of Otolaryngology-Head and Neck Surgery's 2015 guideline on allergic rhinitis, which addressed environmental controls.

"For those who have significant allergy symptoms and/or asthma, environmental controls to reduce exposure may be helpful," she said.

remove pets from homes or at least limit their access to bedrooms; and

seal entry points and eliminate nesting places for pests, as well as remove their food and water sources.

"Implementation of environmental controls may be challenging for many families," Frost said. "If a family physician feels it will benefit the family, the recommended changes should be part of a shared decision-making process, incorporating changes that the family is willing and able to make."

Frost added that intranasal steroids and non-sedating antihistamines are the mainstays of treatment for most individuals with allergic rhinitis.

Study Details

Using data from the 2005-06 National Health and Nutrition Examination Survey (NHANES), researchers studied levels of allergens from eight common sources -- cat, dog, cockroach, mouse, rat, mold and two types of dust mite allergens -- in the bedrooms of nearly 7,000 U.S. homes.

Analysis showed having pets and pests in the home was associated with high levels of indoor allergens. In addition, housing situations such as mobile homes, older homes, rental homes and homes in rural areas elevated exposure to multiple allergens.

Variability in exposure levels to individual allergens was tied to age, sex, race, ethnicity and socioeconomic status, and significant differences were noted between geographic locations and climatic conditions.

"For example, elevated dust mite allergen levels were more common in the South and Northeast and in regions with a humid climate," the news release said. "Levels of cat and dust mite allergens were also found to be higher in rural areas than in urban settings."

Because the 2005-06 NHANES was the first study to compare national allergen exposure and sensitization levels, the research team in the new study compared allergen exposure and sensitization patterns, as well.

Although males and non-Hispanic blacks were less likely to be exposed to multiple allergens, sensitization was more common in these groups compared with females and other racial groups, respectively.

Patterns also were different between urban and rural settings, with rural areas having more exposure to several elevated allergens and urban areas having higher sensitization rates.

Dust mite allergen exposure and sensitization was highest in the Southern and Northeastern regions; exposure and sensitization to the cockroach allergen was most prevalent in the South.

Researchers concluded that the relationships between allergen exposures, allergic sensitization and disease are complex. Additionally, studies are currently being conducted to figure out how allergen exposures interreact with other environmental and genetic factors that lead to asthma and allergies.